Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Fri, 25 Oct 2019 22:43:54 +0200 (CEST)
From:   Thomas Gleixner <tglx@linutronix.de>
To:     Stephen Hemminger <stephen@networkplumber.org>
cc:     Andy Lutomirski <luto@kernel.org>, dev@dpdk.org,
        Peter Zijlstra <peterz@infradead.org>,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: [dpdk-dev] Please stop using iopl() in DPDK
In-Reply-To: <20191025091310.05770edc@hermes.lan>
Message-ID: <alpine.DEB.2.21.1910252232590.1905@nanos.tec.linutronix.de>
References: <CALCETrVepdYd4uN8jrG8i6iaixWp+N3MdGv5WhjOdCr9sLRK1w@mail.gmail.com> <20191025091310.05770edc@hermes.lan>
User-Agent: Alpine 2.21 (DEB 202 2017-01-01)
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Fri, 25 Oct 2019, Stephen Hemminger wrote:
> On Thu, 24 Oct 2019 21:45:56 -0700
> Andy Lutomirski <luto@kernel.org> wrote:
> > 3. Use ioperm() instead of iopl().
> 
> Ioperm has the wrong thread semantics. All DPDK applications have
> multiple threads and the initialization logic needs to work even
> if the thread is started later; threads can also be started by
> the user application.
> 
> Iopl applies to whole process so this is not an issue.

No. iopl is also per thread and not per process. That has been that way
forever. The man page is blantantly wrong.

Both iopl and ioperm are inherited on fork.
 
Thanks,

	tglx